Sarsen boulders lie scattered in substantial “drifts” across the landscape of the Marlborough Downs near Avebury.

By contrast, close to Stonehenge there are almost none. This is one of the reasons why most archaeologists believe that the large sarsens for the monument were not locally sourced.

There are, however, a few examples of substantial sarsens dotted about Salisbury Plain within a couple of miles of Stonehenge. And there are tantalising hints that others used to exist.

The most obvious, and easily accessible, is the Cuckoo Stone. This stone is about 2m long by 1.5m wide by 1.5m thick and lies in the field immediately west of Woodhenge.

The Stonehenge Riverside Project excavated around the Cuckoo Stone in 2007 and discovered that the stone once had been set upright right next to the hollow in which it had originally formed.

Close by were two neolithic pits containing pottery worked…